to prepare the mushrooms
Preheat oven to 350°F.
Heat a cast-iron skillet over medium-high heat. When skillet is hot, add oil, and spread oil around pan.
Add one cluster of mushrooms at a time, placing in skillet, then sliding in a circular motion to coat bottom surface with oil. Let mushrooms cook for a few minutes, then add a second cast-iron pan to the top to press.
Apply some pressure to the top skillet, and make sure the mushrooms are being pressed evenly. The mushrooms will start to release their liquid. When the liquid reduces a bit, remove the top skillet and turn the mushroom clusters. Seared side should be beautifully caramelized and charred.
Slide clusters around to make sure the bottoms are coated with oil, and let sizzle for a few minutes, then press with second skillet. When most of the liquid is gone, remove top skillet and sprinkle the clusters with half of the BBQ seasoning. Turn the mushrooms so the seasoned side is down, and add a splash of oil. Press with second skillet again.
After a few more minutes of pressing, remove skillet, and season second side with remaining BBQ seasoning. Turn mushrooms so newly seasoned side is down, and press again.
After both sides are nicely seasoned and charred, remove from heat.
Add mushrooms to a medium mixing bowl. Add BBQ sauce and sriracha, and toss to combine and coat mushrooms evenly.
Pour mushrooms and sauce into bottom of prepared baking dish. Bake for 30 minutes until sauce is bubbling.
Let slightly cool while you toast your buns. Slice once cooled.
to assemble and finish
Heat a cast-iron skillet over medium heat.
Add oil and rotate pan to spread oil evenly. Slice sandwich buns in half, and place sliced side down in skillet. Move buns around skillet to coat with oil.
Cover skillet with lid and let buns toast for about 2 minutes.
To the bottom bun, add some of the sriracha mayo. Add tomato slices, BBQ mushrooms, then lettuce shreds.
Spread any remaining sriracha mayo on the top bun, and close sandwich. Serve immediately.
for the mushrooms
3 T oil, divided
4 clusters of pink oyster mushrooms, ends removed
1 T dry BBQ seasoning, divided
1 C of your favorite BBQ sauce
2 T siracha hot sauce
pinch of coarse sea salt
pinch of pepper
for assembly and finishing
2 t oil
2 sandwich buns
2 T of plant-based mayo, combined with desired amount of sriracha
1 tomato, sliced
½ C romaine lettuce, shredded